There are known in the art, for example from EP-A-0561444, machines for the formation of tablets of cosmetic product. Said machines comprise feeding means (for example feeding hoppers) of a cosmetic product in powder to a conveyor belt and levelling means (fixed divider panels) placed downstream from the feeding means to determine the formation of a levelled layer of cosmetic product that is moved by said conveyor belt. The tablets are formed by portioning the levelled layer of cosmetic product by means of hollow punches movable vertically that, from a raised position, are lowered so as to immerse them in the layer of cosmetic product; pressure pistons slidable inside the hollow punches then compress the portion of cosmetic product contained in the hollow punch itself against the conveyor belt, and the hollow punches, containing the tablet of cosmetic product, are then raised again and moved to an area of deposition of the tablets of cosmetic product in special containers.
In such machines, the belt forming the conveyor belt is in a material impermeable not only to the cosmetic powder but also to air, and in the area of formation of the tablets under said belt there is a metal supporting plate that reacts against the thrust of the hollow punches and of the corresponding pressure pistons.
A drawback of these machines is that the air present in the layer of cosmetic powder and in the hollow punches, not finding a way of escape during the compression of the portions of cosmetic product for the formation of the tablets, cause the inglobation of the particles of air in the product and consequent stratifications and other irregularities in the tablets of cosmetic product.